1. Field of the Invention
The present invention relates to a joining tool, and particularly to a tool for aligning and joining sections of waterstop at a 90.degree. angle, or end-to-end at a 180.degree. angle, the edges of the waterstop being cut at a 45.degree. and 90.degree., respectively, with respect to each longitudinal axis.
2. Description of the Related Art
Waterstops are typically used in the construction of concrete structures used for the containment of fluids, such as dams, water treatment plants, chemical refineries, etc., and also in highway construction. Waterstops provide a watertight seal between concrete slabs. Although waterstops may be made from rubber, in recent years waterstops have been made from thermoplastic materials, such as polyvinyl chloride (PVC), having high tensile strength and elongation. An example of waterstop construction is shown in U.S. Pat. No. 4,285,180, issued Aug. 25, 1981 to Hinton, et al.
Waterstops are placed at the junction between adjacent concrete slabs, one end of each section being placed each of the slabs between pours. It is frequently necessary to join one section of waterstop to another using conventional techniques for welding plastics. While some sections of waterstop must be butted together end to end, still other joints between different sections of waterstop must be at a 90.degree. angle to each other, the edges of the sections being mitred at a 45.degree. angle. It is important to maintain a clean, uniform seam at the joints in order to prevent water seepage or damage at the joints due to hydrostatic pressure.
The typical procedure for joining sections of waterstops involves cutting the sections at the required angle, usually with the aid of a mitre box. The ends of the two sections are then heated simultaneously. The ends are then pushed together and held in contact with each other for a sufficient period of time for the joint to cool and harden, a seam being formed at the joint. There are some problems associated with the procedure. Frequently during cutting in the mitre box or during the process of heating and pressing the two sections together, the center bulb of the waterstop sections becomes deformed due to a lack of support for the sidewalls of the bulb. It also may be difficult to manually align the ends of the sections without a template or guide due to variations in the thickness and width of the sections, or the softness and malleability of the heated ends of the sections.
Such problems may lead to failure of the joint. There is therefore a need for a tool which may be used as a template in cutting sections of waterstop at either a 90.degree. or a 45.degree. angle. There is a further need for a tool which may be used to guide the heated ends of the waterstop sections together to for a joint at either end-to-end at a 180.degree. angle, or at a 90.degree. angle, compressing the heated ends of the waterstop to form a uniform raised ridge at the seam. It is further desirable that such a tool be economical to manufacture, easy to use, and portable for use at the construction site.
A few devices have been proposed for joining sections of waterstop. U.S. Pat. No. 4,539,064, issued Sep. 3, 1985 to Andruchiw, et al., describes a device for joining two sections of waterstop end-to-end with a lap joint, the device being a jig enclosing the joint, with complementary slots on the top and bottom side of the jig. A router or other cutting device is used to cut complementary rebates on the top and bottom surfaces of the waterstop, each of the rebates extending to one-half the thickness of the two sections. The two sections are approximated into a lap joint with an electric heating element placed between the two sections, and a current is passed through the heating element in order to fuse the sections together. The device is not adapted for forming joints with the edges mitred at a 45.degree. angle.
U.S. Pat. No. 4,867,835, issued Sep. 19, 1989 to W. J. Poole, teaches an apparatus for splicing waterstops comprising a table with two moveable sections spring biased towards each other and a heating element which may be interposed between cut ends of the waterstops. The work pieces are clamped to the table top by clamps having differently shaped feet for different cross-sectional shapes of waterstop. A mitre joint may be formed by clamping the pieces at an angle, presumably insuring proper alignment by eyeballing the joint.
U.S. Pat. No. 5,329,094, issued Jul. 12, 1994 to Murphy, et al., shows a radiant heater for joining sections of waterstop, the radiant heater having two quartz heating tubes disposed horizontally and stacked in a column with reflectors disposed above and below the quartz tubes. Heated is radiated laterally to heating zones in order to melt the edges of the waterstop sections, which are then joined and cooled. The invention is not specifically directed to templates for cutting and joining waterstop sections at an angle to one another.
Various general purpose mitre boxes and corner clamps, particularly for carpentry and woodworking, are known, such as the devices shown in U.S. Des. Pat. No. 271,660, issued Dec. 6, 1983 to Elmore, et al., U.S. Pat. No. 3,835,616, issued Sep. 17, 1974 to G. L. Van Wieringen, U.S. Pat. No. 3,872,761, issued Mar. 25, 1975 to Gutowski, et al., U.S. Pat. No. 4,437,375, issued Mar. 29, 1984 to Elmore, et al., and U.S. Pat. No. 4,646,801, issued Mar. 3, 1987 to T. E. Hines.
Other template devices for cutting and splicing various workpieces include U.S. Pat. No. 3,711,947, issued Jan. 23, 1973 to J. R. Mason (shears and guide for cutting beveled edges in automobile molding); U.S. Pat. No. 4,736,523, issued Apr. 12, 1988 to J. Hanning (saw guide for making cross cuts with a portable saw); U.S. Pat. No. 4,741,235, issued May 3, 1988 to J. G. Price (jig for cutting and splicing conveyor belts at acute angle other than 90.degree.); U.S. Pat. No. 4,919,384, issued Apr. 24, 1990 to G. Grimberg (guide for portable cutting device including rails and a slidable carriage); U.S. Pat. No. 5,176,058, issued Jan. 5, 1993 to N. E. Skelly (fixture used with a rip fence and a table saw); and United Kingdom Patent No. 904,015, published Aug. 22, 1962 (cutting and splicing device for cutting film at 90.degree. angle or recording tape at 45.degree. angle).
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a waterstop joining tool solving the aforementioned problems is desired.